The present invention relates to tetrachannel cross-section staple fibers, as well as yarn, fabrics and fiberfill made therewith and the process of making such staple fibers.
Polyethylene terephthalate (xe2x80x9c2GTxe2x80x9d) and polybutylene terephthalate (xe2x80x9c4GTxe2x80x9d), generally referred to as xe2x80x9cpolyalkylene terephthalatesxe2x80x9d, are common commercial polyesters. Polyalkylene terephthalates have excellent physical and chemical properties, in particular chemical, heat and light stability, high melting points and high strength. As a result they have been widely used for resins, films and fibers, including staple fibers and fiberfill comprising such staple fibers.
Synthetic fibers made from 2GT are well known in the textile industry. Further, the properties and processing parameters of 2GT polymer are well known. Such synthetic fibers are commonly classified into two groups: (1) continuous filaments and (2) discontinuous fibers, often referred to as xe2x80x9cstaplexe2x80x9d or xe2x80x9ccutxe2x80x9d fibers. Common end-use products made from 2GT staple fibers include yarn, fabric and fiberfill.
2GT staple fibers are desirable in such end-use products because of certain characteristics. For example, fabric and yarns from staple fibers from 2GT are known to produce yarns having desirable characteristics for downstream processing as disclosed by Aneja in U.S. Pat. No. 5,736,243. For instance, such fibers are suitable for processing on worsted systems. Furthermore, yarns made from such fibers are useful in manufacturing lightweight fabrics having good moisture wicking ability. Moisture wicking is desirable in fabrics used in many types of clothing items, e.g., sporting apparel, because they help keep moisture away from the wearer. Similarly, lightweight fabrics are desirable because they are less cumbersome than heavier fabrics.
Certain 2GT staple fibers are even more desirable in such end-use products because of special shape characteristics. For example, U.S. Pat. No. 5,736,243 discloses fabric and yarns of 2GT staple fibers having a tetrachannel cross-section, more specifically a scalloped-oval cross-section with channels that run along the length of the filament. Yarns made from such fibers are particularly useful in manufacturing lightweight fabric having good moisture wicking ability.
Recently, polytrimethylene terephthalate (3GT), also called polypropylene terephthalate, has achieved growing commercial interest as a fiber because of the recent developments in lower cost routes to 1,3-propane diol (PDO), one of the polymer backbone monomer components. 3GT has long been desirable in fiber form for its disperse dyeability at atmospheric pressure, low bending modulus, elastic recovery and resilience. However, the manufacture of 3GT staple fiber suitable for high-strength, high-elasticity yarns poses a number of special problems, particularly in obtaining satisfactory fiber crimp and yarn strength. The solutions to these problems developed over the years for 2GT or 4GT fibers frequently do not apply to 3GT fibers because of 3GT""s unique properties.
U.S. patent application Ser. No. 09/795,518 (now U.S. Pat. No. 6,383,632) and Ser. No. 09/795,520, both filed Feb. 28, 2001 (published as U.S. 2001/0030377 A1), and both of which claim priority from U.S. patent application Ser. No. 09/518,759, filed Mar. 3, 2000, now abandoned, are directed to 3GT drawn yarn and a process of making the drawn yarn from 3GT partially oriented feed yarn, as well as 3GT fine denier partially orient undrawn feed yarn and its preparation. The very fine filament yarns are suitable for warp drawing, air jet texturing, false-twist texturing, gear crimping, and stuffer-box crimping, for example. Tows made from these filament may also be crimped, if desired, and cut into staple and flock.
U.S. patent application Ser. No. 09/796,785, filed Mar. 1, 2001 (published as U.S. 2001/0033929 A1), which claims priority from U.S. Provisional Patent Application Serial No. 60/187,244, filed Mar. 3, 2000, is directed to 3G direct-use yarns comprising non-round filaments and a process for spinning such yarn. The non-round cross-section yarns include those cross-sections described in the art as xe2x80x9cocta-lobalxe2x80x9d, xe2x80x9csunburstxe2x80x9d (also known as xe2x80x9csolxe2x80x9d), xe2x80x9cscalloped ovalxe2x80x9d, xe2x80x9ctri-lobalxe2x80x9d, xe2x80x9ctetra-channelxe2x80x9d (also known xe2x80x9cquatra-channelxe2x80x9d), xe2x80x9cscalloped ribbonxe2x80x9d, xe2x80x9cribbonxe2x80x9d, xe2x80x9cstarburstxe2x80x9d, etc.xe2x80x9d Example II is directed preparing a direct-use yarn having filaments of varying cross-sections. Half of the resulting filaments had an octalobal cross-section and half had a sunburst cross-section. Example III is directed to octa-lobal cross-section filaments. FIGS. 2 and 3 are schematic diagrams of hypothetical filaments having an octalobal cross-section. FIG. 5 is a micrograph (750xc3x97 magnification) of filaments having an octa-lobal cross-section prepared as described in Example III.
U.S. patent application Ser. No. 09/518,732, filed Mar. 3, 2000 (issue fee paid) (now U.S. Pat. No. 6,287,688) and Ser. No. 09/795,933, filed Feb. 28, 2001 (published as U.S. 2001/0030378 A1), are directed to a 3GT partially oriented yarn, a process for spinning a stable 3GT partially oriented yarn, and a process for continuous draw-texturing a 3GT partially oriented yarn. The yarns can have round, oval, octa-lobal, tri-lobal, scalloped oval, and other shapes, with round being most common. Sample IIB (See, Example II, Table 2) is an octa-lobal partially oriented yarn.
JP 11-189938 teaches making 3GT short fibers (3-200 mm), and describes a moist heat treatment step at 100-160xc2x0 C. for 0.01 to 90 minutes or dry heat treatment step at 100-300xc2x0 C. for 0.01-20 minutes. In Working Example 1, 3GT is spun at 260xc2x0 C. with a yarn-spinning take-up speed of 1800 m/minute. After drawing the fiber is given a constant length heat treatment at 150xc2x0 C. for 5 minutes with a liquid bath. Then it is crimped and cut. Working Example 2 applies a dry heat treatment at 200xc2x0 C. for 3 minutes to the drawn fibers.
JP 11-107081 describes relaxation of 3GT multifilament yarn unstretched fiber at a temperature below 150xc2x0 C., preferably 110-150xc2x0 C., for 0.2-0.8 seconds, preferably 0.3-0.6 seconds, followed by false twisting the multifilament yarn. This document does not teach a process for making a high tenacity crimped 3GT staple fiber.
U.S. Pat. No. 3,584,103 describes a process for melt spinning 3GT filaments having asymmetric birefringence. Helically crimped textile fibers of 3GT are prepared by melt spinning filaments to have asymmetric birefringence across their diameters, drawing the filaments to orient the molecules thereof, annealing the drawn filaments at 100-190xc2x0 C. while held at constant length, and heating the annealed filaments in a relaxed condition above 45xc2x0 C., preferably at about 140xc2x0 C. for 2-10 minutes, to develop crimp. All of the examples demonstrate relaxing the fibers at 140xc2x0 C.
EP 1 016 741 describes using a phosphorus additive and certain 3GT polymer quality constraints for obtaining improved whiteness, melt stability and spinning stability. The filaments and short fibers prepared after spinning and drawing are heat treated at 90-200xc2x0 C., but are not crimped and relaxed. It states (page 8, line 18) that the cross-sectional shape of the fiber is not particularly limited and may be round, trilobal, flat, star-shaped, w-shaped, etc., and either solid or hollow. WO 01/16413, to the same applicant, claims special advantages for a 3GT fiber extruded with a convex-modified trilobal cross-section.
All of the documents described above are incorporated herein by reference in their entirety.
None of the cited documents teach a process for making a tetrachannel 3GT staple fiber, nor teach the special advantages of such a 3GT staple fiber.
This invention comprises a poly(trimethylene terephthalate) staple fiber having a tetrachannel cross-section. Preferably the tetrachannel cross-section comprises a scalloped-oval shape with grooves.
Preferably the poly(trimethylene terephthalate) fiber has a tenacity of 3 grams/denier (2.65 cN/dtex) or higher. Preferably, poly(trimethylene terephthalate) fiber has a crimp take-up of 10% to 60%.
Preferably the above poly(trimethylene terephthalate) fiber is made by a process comprising the melting of a poly(trimethylene terephthalate) polymer, spinning the melt at a temperature of 245xc2x0 C. to 285xc2x0 C., quenching the fibers, drawing the fibers, crimping the fibers using a mechanical crimper, relaxing the crimped fiber at a temperature of 50xc2x0 C. to 120xc2x0 C., and then cutting the fibers to a length of about 0.2 to 6 inches (about 0.5 to 15 cm).
The staple fibers from the above process have a crimp take-up of 10-60% and a tenacity of at least 3 grams/denier (2.65 cN/dtex).
The invention is also directed to blends of the staple fibers of the invention and cotton, 2GT, nylon, lyocel, acrylic, polybutylene terephthalate (4GT) and other fibers.
The invention is also directed to a yarn made from a poly(trimethylene terephthalate) staple fiber having a tetrachannel cross-section. The invention is further directed to a fabric made from such a yarn. Preferably the fabric has a dye uptake of at least 300%.
The invention is also directed to nonwoven, woven and knitted fabrics made from such fibers and such blends. The invention is further directed to yarns made from such blends, and woven and knitted fabrics made therefrom, as well as fiberfill made from such blends.
The invention is further directed to fibers, yarn and fabric, particularly knitted fabric, with excellent wicking and/or pilling performance. A preferred fabric, preferably a knitted fabric, preferably has a wicking height of at least 2 inches (5 cm) after 5 minutes, preferably at least 4 inches (10 cm) after 10 minutes, preferably at least 5 inches (13 cm) after 30 minutes. The preferred fabrics have fuzzy pills (as opposed to hard pills), which are considered preferable as they result in less pill sensation.
The invention is also directed to the fiberfill webs, batts or products comprising the staple fibers.
The invention is further directed to methods for making the poly(trimethylene terephthalate) yarns, fiberfill webs, batts and products, and fabrics.